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40 Gallon Breeder Tank: Info & Complete Setup Guide

One of the prerequisites for successfully breeding fish is to provide them with the ideal environment, and a 40-gallon breeder tank just so happens to accommodate most freshwater species and certain saltwater fish.

Breeding fish, however, does not come easy, at least when it comes to the majority of fish species out there. It takes a lot of skill and patience to maintain the ideal environment.

It’s even more challenging if you’ve never had any experience with breeding fish before.

When it comes to breeding, the general rule of thumb is to provide your fish with ample enough space. Of course, a 40-gallon breeder tank is overkill for certain species, like the guppy and molly since they’re livebearers,

But the tank’s size becomes especially important when you are breeding fish such as clownfish and cichlids. Other fish you can breed with this include the armored catfish and the driftwood catfish.

The best part about this tank is that it also provides an ideal environment for invertebrates such as ghost shrimps and cherry shrimps.

In this guide, we will give a brief overview of some of the best tanks we came across and which fish are ideal to breed in an aquarium of this size.

What are 40 gallon breeder tank dimensions?

You must be wondering how big is a 40-gallon breeder tank. The exact measurements of each 40-gallon aquarium will vary based on the manufacturer. Most tanks should be 18″ wide, 16″ tall, and 36″ in length.

In the case of the standard non-breeding 40-gallon tank, you can get away with a shorter height.

You may have to adjust the tank’s water levels in some cases, so the breeding tank’s exact dimensions will differ. They are, for the most part, bigger in height.

Best 40 Gallon Breeder Tanks

Let’s start with the three best tanks for breeding.

Aqueon 40 Gallon Breeder Tank

The Aqueon 40-gallon breeder aquarium is usually recommended by experts as an excellent starter choice. It’s ideal for fishkeepers who plan to add their equipment and are relatively barebones at a cursory glance. This tank is designed to last for decades.

It comes equipped with very durable glass that can take quite a beating.

The edges are reinforced with silicone to prevent any chances of a leak. All in all, this is an extremely durable tank that will last you several years.

Its manufacturer, Aqueon, has acquired a pretty good reputation among fish breeders as the go-to solution for tanks of all sizes and styles.

Can purchase The 40-gallon variant of this tank with an oak or black trim. Moreover, it features a braced frame in the middle of the tank to minimize tank bowing chances.


  • It is pretty tall, which allows you to alter the water levels according to your species
  • It doesn’t feature any extra equipment allowing you to add your items to it
  • It comes in two different color choices
  • The manufacturer is known for producing high-quality goods


  • The price tag may be too steep for beginners
  • The tank does not come with a lid, and that can be a deal-breaker for most aquarists

SeaClear 40 Gal Acrylic Aquarium Combo Set

This 40-gallon breeding tank comes with all the necessary tools built into it. It includes lighting and a reflector. Its defining quality is the build quality of the glass, which is made from acrylic.

The result is more durable while being exceptionally lightweight. This tank is clearer than traditional glass because of the acrylic material.

In general, acrylic tanks are much more durable and can withstand all kinds of damage. The glass is very resistant to cracking and chipping. It is a valuable quality in a breeding tank since it’s always under inspection by fishkeepers, which may increase the chances of damage.

Can use this tank for both freshwater and saltwater species.

The main reason for recommending this fish tank is the warranty by SeaClear, the manufacturer – this product boasts a lifetime warranty. It means your investment is safe for years to come.


  • The acrylic glass is far superior to traditional offerings
  • It comes with a lifetime warranty, which can secure your investment
  • Improved visibility
  • You can buy this tank with three background choices


  • There are two openings on the top of this tank, which can become a problem if your fish are known for being jumpers.

SeaClear 46 gal Bowfront Acrylic Aquarium

Thanks to the unique bow shape, the 40-gallon bow front tank is slightly bigger than your regular ‘flat’ tank. Traditional tanks have flat fronts and feature a square or rectangular shape. But this tank features a curved front, which may be a good choice for you.

The bow front offers a bulging effect on the inside of the tank. It provides a unique inside view of the tank and looks a lot cooler in any room. There is one drawback, though. Most cameras will struggle to try to capture high-quality photographs.

From the perspective of a breeder, this tank makes your job a lot easier because you’ll have an easier time keeping track of breeding, eggs, and fish fry.

Furthermore, can use this tank for both saltwater and freshwater fish species.

The manufacturer SeaClear is known for providing high-quality tanks and a generous lifetime guarantee.


  • Visually better than most tanks thanks to the bow front
  • Seamless corners that make breeding easier
  • The tank is made of acrylic, which is more durable and lightweight
  • The tank is less likely to chip or break than a traditional glass tank


  • The top is not fully covered, which means your fish are more likely to escape
  • The tank does not come with light fixtures

Equipment for a 40-Gallon Breeder Aquarium

The type of equipment you introduce into your tank will play a massive role in inbreeding. Any resulting fry or juvenile fish from the breeding process will need a place to call home, so investing in the right equipment is vital here.

Let’s get down to brass tacks.


The essential piece of equipment you should invest in is the filter. It creates the ideal environment for fish and gets rid of the bioload generated over time (thus keeping a check on the tank’s nitrate levels).

More importantly, the filter regulates the distribution of nutrients in the aquarium to create a proper nitrogen cycle.

The filter is also important because it can use to create flow in the tank. It can create movement in the water, which is very important for certain breeding species.

One good place to start is the C Power Filter by Fluval. It can work in a 70-gallon tank.


The temperature can make or break your breeding cycle. In most cases, the ambient temperature won’t provide your fish with a consistent temperature.

It becomes even more important during the breeding seasons and necessitates an artificial way to influence the temperature.

It is worth noting that some saltwater and freshwater fish won’t start to breed until the tank’s temperature is increased to a certain point. It is where a heater comes in.

Before choosing a heater, make sure to provide your specific fish species with the ideal temperature. Not all heaters are built the same.

Some are good at significantly different ranges. Bonus points if you can invest in a heater that allows you to easily adjust the temperature with the click of a button.

Our recommendation for a 40-gallon breeding tank is this Fluval E200 Advanced Electronic Heater. You can buy it in three different ranges, 100 watts, 200 watts, and 300 watts.

Moreover, it features an LCD temperature display that can show the temperature in both Celsius and Fahrenheit, at ranges from 68 to 93°.

It comes with fast heat technology with a safety shut-off, thus protecting your fish from overheating should the device malfunction (not that it ever happens).


The tank stand is a fundamental piece of equipment used to provide stability to the tank and contributes to the décor.

More importantly, it provides storage space for your foods, chemicals, plumbing, and equipment.

Aquarium stands come in a variety of shapes and sizes, so you should be able to find the right one for the tank. It is worth noting that they take up a lot of space, and you’ll need more room to keep them in.


As you may have already noticed, a typical 40-gallon breeder aquarium does not come with a lid by default. They’re either completely open or feature small openings.

It increases the possibility of your fish escaping from their enclosure and dying as a result. But there’s more to a lid than merely blocking your fish’s escape route. For instance, can use them to provide shelter to the fish from excessive lighting.

A lid becomes particularly necessary in tanks where the fish are stressed out and are prone to jumping out.

Tank Setup

Creating the ideal breeding environment requires you to pay a bit more attention. You have to clean the water and remove dust build-up. All the steps you take will have to be aligned with the species you plan to breed in the aquarium.

The most crucial aspect of your tank is the filtration system, substrate, heater, and lighting. In a non-breeding tank, these conditions remain unchanged throughout the day, but you will have to adjust the default settings depending on the day’s time in a breeding tank.

Let’s start with the substrate. It is crucial because certain fish species will swim to the tank’s bottom to create their nests and lay their eggs. The substrate should not contain any sharp edges that could hurt these fish.

More importantly, sharp edges on the substrate could quickly kill fry because they will spend most of their time in the tank’s lower columns.

With the substrate in place, it’s time to choose the right decorations. It depends entirely on the species you plan on breeding.

Some fish need tanks populated with dense plantations and lots of rockwork and caves to hide. Simultaneously, others may only require lots of swimming space and a soft substrate to land on.

Once you’ve decided on the decorations and substrate, it’s time to install the heater and the filter.

Every filter has its installation instructions, so make sure to read them before installing the filter in the tank.

In the case of external filters, you’ll have to take care of a few plumbing errands. By contrast, internal filters will usually only have one power cable.

Now, for the most critical part: adding the water. The water level depends on the type of fish species you add to the tank. Some fish species prefer an increase in the water level during mating, while others require external conditions to stimulate spawning.

Finally, it’s time to install light fixtures and a lid. Some lids come with lights attached, while others don’t.

Once all your equipment is set up, switch the heater, filter, and lights on and allow at least one month for the tank to properly establish a nitrogen cycle before adding your fish.

Which fish can you breed in a 40-gallon breeder tank?

Your 40-gallon aquarium should create the ideal environment for breeding, for certain species, of course. At this size, you can breed some of the most challenging species.

Most fish classified as ‘small’ can be bred in this tank, including a few larger species. It applies to both freshwater and saltwater fish.

Should you choose smaller fish, it is worthwhile considering the use of dividers to divide the tank into various sections to give you more options.

Examples of small fish you can breed this way include Guppies, Bettas, Swordtails, and Danios.

Some of the larger fish that you can breed include catfish, cichlids, and even shrimps.

The main advantage of buying a 40-gallon tank is that you can introduce different species and keep them under similar conditions, all the while ensuring they have enough space to roam around.

It is guaranteed to make your tank look stunning and productive, and it will also increase the success rate of breeding.

Every fish species has its breeding conditions. Make sure you refer to those before adding them to your tank. Also, make sure they’re compatible with their tank mates.

Tank Temperature

This section requires an article of its own, but we thought it’s essential to include a few common smaller fish that aquariums will likely try to breed.

Ideal Breeding Temperature for Guppies

Guppies prefer temperatures ranging from 73 to 77 Fahrenheit. To stimulate spawning, increase the temperature of the breeding tank to 80° Fahrenheit. It will encourage breeding. Keep the same pH level.

Ideal Breeding Temperature for Tetras

Neon Tetras prefer the breeding water temperature to be around 76° Fahrenheit. Should slightly lower their Ph to between 5 and 6, give special care to the lighting requirements for the fish and their fry.

Ideal Breeding Temperature for Goldfish

To initiate the breeding process in Goldfish, you should target a temperature in the range of 69 to 73° Fahrenheit.

Caution: Make sure you increase the temperature in small increments to get to your target threshold. Do not increase more than 2° a day because fish are notoriously vulnerable to significant temperature changes.

For a goldfish, this means having to wait at least ten days to increase the temperature to stimulate breeding conditions.

But this is better than having to kill the poor creature! When you take your time to increase the temperature, you’re also giving your fish’s biological system to adapt to the task appropriately.

40 Gallon Quarantine Tank for Sick Fish

If you’re serious about breeding your fish, you will have to buy a quarantine tank because certain fish will species get sick from time to time. It is important to isolate them from one another to prevent the spread of disease. Do not use your 40-gallon tank to quarantine your fish or care for sick fish.

It is not wise to administer medicine to the entire fish stock if they’re not sick, not to mention that it can completely ruin the breeding environment. For best results, get a cheap quarantine tank to be prepared for sick fish or fried fish.